Replaceable driving lugs for crawler tread



March 7, 1967 T, MGFAYDEN 3,307,882

REPLACEABLE DRIVING LUC-s FOR CRAWLER TREAD I Filed June 8. 1964 Arran/5X United States Patent 3,307,882 REPLACEABLE DRIVING LUGS FOR CRAWLER TREAD Thurman L. McFayden, 1463 E. Vernon Road, Philadelphia, Pa. 19150 Filed June 8, 1964, Ser. No. 373,410 2 Claims. (Cl. 30S- 56) This invention relates 'to a tractor tread, and more particularly, to an improved method of renovating the same.

Treactor treads for road building machinery and other heavy machinery consist of articulated sections, Ithe outer surfaces of which engage the road, and the inner surfaces of which are engaged by the driving wheels of the vehicle. In some embodiments, each tread section includes two -pairs of spaced lugs, adapted to be engaged by driving lugs, or blocks, on either side of the driving wheel with the rim of the wheel disposed between said pairs of lugs. In such an arrangement, one pair of lugs is engaged by the driving blocks for forward movement of the vehicle, and the other pair of lugs is engaged by the driving blocks during reverse movement of the vehicle. Because of the heavy load and the resultant friction to which they aresubjected, Vthe lugs wear out rather rapidly.

It has heretofore been the practice `to renovate a tread section, the lugs of which have worn off, by re-building the lugs back to the original size and shape by depositing molten metal on the stumps of Ithe lugs. The lugs are of substantial dimensions, and it takes much time and labor to rebuild the lugs to their original size. Also, the lugs have a specific initial contour, and it requires the services of an expert welder to produce the desired contour, yand when the lugs have been thus re-built, they must then be ground to the proper finish. The cost of renovating four lugs on each tread section is quite high and is resorted to only because the cost of discarding a tread section which is still usable, is even higher.

It is also well known that depositing molten metal must be carried out under controlled temperature, and it is therefore a slow process; whereas, burning metal off, is carried out under high temperature and is a quick process. Also, burning off metal takes less skill than depositing it.

The object of this invention is to produce a replacement unit which can be quickly and inexpensively applied to a tread and which replaces a pair of worn out lugs at one time.

A still further object is to produce a new method of replacing the worn out lugs.

The full nature of the invention will be understood from the following specification .and the accompanying drawings, in which:

FIG. 1 is a perspective view of a tread section embodying the invention.

FIG. 2 is an enlarged side elevational view of one of the replacement units embodying this invention.

FIG. 3 is an enlarged section looking in the direction of line 3 3 on FIG. 1.

FIG. 4 is a phantom side elevational view showing one of the conventional lugs which is replaced by my invention. l

As shown in FIG. 1, a tread section of the ty-pe referred to includes a stamping, a casting, or a forging 10, which is of any desired shape and contour, and which is provided with any desired configuration on its inner surface, that is, the surface engaged by the driving wheel, and on its outer surface, that is, the surface which engages the 3,307,882 Patented Mar. 7, 1967 ICC road. The shape and size ofthe tread section, as well as of the configurations referred to, form no part of the present invention and are therefore not shown or described.

A conventional tread section also includes oppositely disposed and spaced bosses 12, which are provided with through openings 14, for receiving connecting pivot pins, not shown, the spaces between the lugs on one side of the tread section being interdigitated with the lugs on an adjacent section, the interconnected sections provide an articulated, continuous track. For the purpose of this invention, it is only necessary to note that the periphery, or rim, of the driving wheel rides on surface 14, and the conventional driving wheel is provided with driving blocks on the opposite vertical sides thereof, which blocks are adapted to engage radially inwardly projecting lugs, such as the lug shown in phantom in FIG. 4. In a conventional tread section, the lugs of FIG. 4 will be located at the points marked 16 and 18 in FIG. 1. It will be noted that the lugs at points 16 will be engaging the driving blocks when the driving wheel moves in clockwise direction to move the vehicle forwardly, and that the lugs at points 18 will be engaged by driving blocks when the driving wheel rotates in counter-clockwise direction to move the vehicle rearwardly, or vice versa. When the conventional lugs shown in broken lines in FIG. 4 wear down, to a point which makes them ineffective for driving the vehicle, it becomes necessary to rebuild them. This has heretofore been done by depositing new metal until the lug is of a slightly greater size than needed so as to provide metal which can be removed during the final grinding operation to produce the exact shape. This is a tedious lprocess and requires the work of an expert.

According to my invention, I burn off the stumps of worn out lugs down to surface 14 and I replace each pair of lugs at points 16 and 18 with a replacement unit such as that shown in FIGS. 2 and 3. The replacement unit of my invention includes a connecting body 22, which carries lugs 16 and 18 which correspond to the conventional lugs at points 16 and 18, and a tapered bottom 24 which, when placed on surface 14, provide V-shaped grooves for receiving welding metal 20.

It will be noted that burning olf the stump of a lug can be done quickly and -without skill, and that lugs 16 and 18' of my unit are of the proper size and shape and need no grinding. Actual experience has shown that the stumps of four lug can be burned ofi and two of my replacement unit can Ibe welded on in just about the time it takes to build up and finish grinding one conven tional lug. In other words, my novel process and replacement unit effect a saving of about three-quarters of the cost of renovating.

In addition to the reduction in the cost of replacement, I also effect an overall reduction in the cost of operation by reducing the time that the vehicle, whose tread section is being replaced, is out of commission.

What I claim is:

1. In combination with a worn metal crawler track tread section wherein the original driving lugs have been removed leaving a fiat upper surface portion, a pair of spaced parallel metal driving lugs positioned longitudinally of the tread section and located substantially centrally of said Itread, each of said lugs comprising an elongate body section having convexly vcurved driving surfaces at opposite ends thereof and having beveled lower edges forming with said flat surface a triangular groove extending the length of and on each laterally opposite side of each of said lugs, and weld metal positioned Nithin said grooves to anchor each of said lugs Ito said iurface.

2. In a process for repairing ya worn metal crawler :rack tread section which comprises four original driving ugs, two of each Ibeing positioned longitudinally of said ',rack, the steps of removing said four lugs leaving a flat Jpper surface portion on said track, placing on said unooth upper surface a pair of spaced parallel metal lriving lugs positioned longitudinally of the tread sec- :ion and located substantially centrally of said tread, each of said lugs comprising an elongate body section having :onvexly curved driving surfaces at opposite ends thereof and having beveled lower edges forming with said at section a triangular groove extending the length of and an each laterally opposite side of each of said lugs, and 15 welding said lugs to the tread section, the weld metal Jeing positioned within said grooves and anchoring each of said lugs to said section.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 8/ 1939 France. 1/1960 France. ll/1957 Sweden.

BENJAMIN HERSH, Primary Examiner. A. HARRY LEVY, Examiner. R. I. JOHNSON, Assistant Examiner. 

1. IN COMBINATION WITH A WORN METAL CRAWLER TRACK TREAD SECTION WHEREIN THE ORIGINAL DRIVING LUGS HAVE BEEN REMOVED LEAVING A FLAT UPPER SURFACE PORTION, A PAIR OF SPACED PARALLEL METAL DRIVING LUGS POSITIONED LONGITUDINALLY OF THE TREAD SECTION AND LOCATED SUBSTANTIALLY CENTRALLY OF SAID TREAD, EACH OF SAID LUGS COMPRISING AN ELONGATE BODY SECTION HAVING CONVEXLY CURVED DRIVING SURFACES AT OPPOSITE ENDS THEREOF AND HAVING BEVELED LOWER EDGES FORMING WITH SAID FLAT SURFACE A TRIANGULAR GROOVE EXTENDING THE LENGTH OF AND ON EACH LATERALLY OPPOSITE SIDE OF EACH OF SAID LUGS, AND WELD METAL POSITIONED WITHIN SAID GROOVES TO ANCHOR EACH OF SAID LUGS TO SAID SURFACE. 